In conjunction with tunnelling or in a mine, cracks in the rock layers often arise around a cavity in a mountain through which for example a future tunnel will run. The cracks weaken the rock in the mountain, which may result in that parts of the mountain may collapse. Therefore actions are needed that reduce the risk for collapse. The actions are usually called rock reinforcement. A common method for rock reinforcement is rock bolting. Rock bolting means that a bolt adapted for rock bolting is fastened in a drilled hole by a molding agent. In this way the rock layers are bonded- and held together so that the risk for collapse is reduced.
WO2012171056 describes an apparatus for injection of a resin in conjunction with rock bolting. The apparatus comprises an injector comprising a valve manifold with shuttle valves arranged in fluid inlets for injection of resin components. The valve manifold comprises also an additional inlet for a flushing fluid. All the tree inlets end in a common cavity that connects the inlets. The valves may be positioned in a position that permits injection of the components into a mixing chamber connected to the valve manifold. The valves may also be positioned in another position that permits supply of the flushing fluid through the additional inlet and the cavity for the purpose to flush the valve manifold and the mixing chamber. One disadvantage with the apparatus in WO2012171056 is that it may be rests of the resin components inside the inlets when the flushing fluid is injected in the valve manifold, which may impair reliability of service of the apparatus.